Impact of pre-annealing time on the growth and properties of Ag2ZnSnSe4 thin films

Abstract

In this study, we demonstrate the pre-annealing treatment of stacked precursors at 250 °C for different durations (5, 10, 15, 20, 30, and 60 min), subsequently selenized at 400 °C for 1 min and correlate its effects on structural, morphological, and optoelectronic properties of Ag2ZnSnSe4 films (AZTSe) with a detailed characterization. After investigating pre-annealing treatment duration, the grown AZTSe films show various binary/ternary phases and appreciable transformation in surface morphology. However, stacked layers pre-annealed for 20 min and selenized at 400 °C for 1 min show a single-phase kesterite AZTSe with two main Raman peaks at 181 and 198 cm−1 with compact and larger grains (~0.53 μm). The bond length and bond angles for single-phase AZTSe films are evaluated using Rietveld refinement of X-ray diffraction data. The core-level X-ray photoelectron spectra confirm the oxidation formula as Ag2+1Zn+2Sn+4Se4−2 and uniform distribution of elements is established by secondary ion mass spectrometer measurements, for precursor films pre-annealed at 250 °C for 20 min and selenized at 400 °C for 1 min. They possess n-type conductivity with a maximum mobility of 79.4 cm2(Vs)−1 and a direct band gap of 1.37 eV.